Effect of Pd content on the isomerization performance over Pd-S2O8 2−/ZrO2-Al2O3 catalyst

Abstract

The effect of Pd content on the performance of the Pd-S2O8 2−/ZrO2-Al2O3 solid superacid catalyst was studied using n-pentane isomerization as a probe reaction, and the catalysts were characterized by FTIR, BET, TG-DTA, H2-TPR, NH3-TPD and XPS. The results showed that an appropriate amount of Pd could promote the formation of acid sites, enhance the acidity of catalyst, improve the redox properties of the catalyst, and delay the decomposition of S2O8 2− effectively. The Pd-S2O8 2−/ZrO2-Al2O3 catalyst with 0.05 wt % Pd exhibited the best catalytic activity for n-pentane isomerization. At the reaction temperature of 200 °C, reaction pressure of 2.0 MPa, weight hourly space velocity of 1.0 h−1, H2/n-pentane molar ration of 4.0, the n-pentane conversion, iso-pentane selectivity and yield reached 61.1, 96.7, and 59.1 %, respectively, the isopentane yield with the Pd-S2O8 2−/ZrO2-Al2O3 increased by 39.1 % compared to S2O8 2−/ZrO2-Al2O3, and no obvious catalyst deactivation was observed within 100 h.